1. Field of the Invention
This invention relates to bicomponent fibers comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate), particularly such fibers having a plurality of longitudinal grooves.
2. Description of Background Art
Polyester bicomponent fibers are disclosed in U.S. Pat. No. 3,671,379 and Published Japanese Patent Application JP08-060442, and non-round polyester fibers are disclosed in U.S. Pat. Nos. 3,914,488, 4,634,625, 5,626,961, 5,736,243, 5,834,119, and 5,817,740. However, such fibers can lack sufficient crimp levels and/or wicking rates, and fibers with improved wicking are still needed for dry comfort, especially in combination with the high stretch desired for today""s apparel.
The present invention provides a bicomponent fiber comprising poly(ethylene terephthalate) in contact with poly(trimethylene terephthalate) wherein the weight ratio of poly(ethylene terephthalate) to poly(trimethylene terephthalate) is at least about 30:70 and no more than about 70:30 and wherein the bicomponent fiber has:
(a) a scalloped oval cross-section selected from the group consisting of side-by-side and eccentric sheath-core;
(b) a cross-section long axis;
(c) a boundary between the poly(ethylene terephthalate) and the poly(trimethylene terephthalate) that is substantially parallel to the long axis, and
(d) a plurality of longitudinal grooves.
In another embodiment, the present invention provides a bicomponent fiber selected from the group consisting of fully-drawn continuous filament, fully-oriented continuous filament, partially oriented continuous filament, and fully-drawn staple wherein the fiber comprises poly(ethylene terephthalate) and poly(trimethylene terephthalate) and has:
a weight ratio of poly(ethylene terephthalate) to poly(trimethylene terephthalate) of at least about 30:70,
a weight ratio of poly(ethylene terephthalate) to poly(trimethylene terephthalate) of no more than about 70:30,
a scalloped oval cross-section selected from the group consisting of side-by-side and eccentric sheath-core,
a cross-section long axis,
a polymer boundary between the poly(ethylene terephthalate) and the poly(trimethylene terephthalate) and substantially parallel to the cross-section long axis, and
a plurality of longitudinal grooves,
wherein:
when the fiber is a fully-drawn filament, it has an after heat-set crimp contraction value of at least about 30%,
when the fiber is a fully-oriented filament, it has an after heat-set crimp contraction value of at least about 20%
when the fiber is a partially oriented bicomponent filament, it has an as-drawn after heat-set crimp contraction value of at least about 10%, and
when the fiber is a fully-drawn staple, it has a tow crimp take-up value of at least about 10%.